Open-end spinning frame

ABSTRACT

An open-end spinning frame ( 1 ) having a spinning rotor ( 3 ), whose rotor shaft ( 4 ) is supported, free of axial thrust, in the bearing wedge of a support disk bearing arrangement ( 5 ) and is fixed in place by means of a magnetic axial bearing ( 18 ). The axial bearing ( 18 ) has a stationary magnetic bearing component ( 27 ) fixed on the bearing housing ( 26 ), and a rotating magnetic bearing component ( 44 ) arranged at the end of the rotor shaft and having at least two annular shoulders ( 46 ) defined by recesses ( 47 ) in the rotor shaft ( 4 ). The sharpness of the annular shoulders ( 46 ) is reduced in the area between their outer circumference ( 58 ) and the adjoining radial faces ( 50 ) of each annular shoulder, e.g., via curved or beveled surfaces in such area, and the base surfaces ( 49 ) of the recesses ( 47 ) are each connected via rounded sections ( 51 ) with the radial faces ( 50 ) of the adjoining annular shoulders ( 46 ).

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of German patent application DE P19955829.9, filed Nov. 20, 1999, herein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to an open-end spinning frame having aspinning rotor with a rotor shaft supported so as to be free of axialthrust in a wedge-like bearing area formed between adjacent pairs ofsupport disks and held in place therein by a magnetic axial bearinghaving a stationary magnetic bearing component fixed in a bearinghousing and a rotating magnetic bearing component arranged at the end ofthe rotor shaft and formed by at least two annular ferromagneticshoulders which are constituted by recesses in the rotor shaft.

BACKGROUND OF THE INVENTION

Spinning units are known in open-end rotor spinning frames wherein therotor shaft of the spinning rotor, which typically revolves at a highnumber of revolutions, is supported in the wedge-like bearing area of asupport disk bearing arrangement and is fixed in place by means of amechanical axial bearing arranged at the end of the shaft. Here, thesupport disk bearing arrangement comprises two pairs of support disksdisposed adjacent one another to define the bearing wedge areatherebetween, with the axes of the support disks offset such that anaxial thrust is exerted on the rotor shaft to constantly urge the rotorshaft against the mechanical axial bearing arranged at its end.

This type of seating of open-end spinning rotors which, for example, isdescribed in German Patent Publication DE-OS 25 14 734, has provenitself in actual use and makes it possible for the spinning rotors toachieve rotational speeds of greater than 100,000 rpm.

However, because of the offset of the support disks, this type ofseating of spinning rotors suffers the disadvantage of increasedfriction occurring between the bearing surfaces of the support disks andthe rotor shaft, which over time leads to heating of the bearingsurfaces of the support disks. Not only are the bearing surfaces of thesupport disks considerably stressed by this frictional heating, butadditional energy is also required to overcome this friction. Moreover,the mechanical axial bearings are subjected to not inconsiderable wear,even when properly lubricated.

Therefore attempts have already been made in the past to replace thesemechanical axial bearings with wear-resistant magnetic bearings. Anaxial magnetic bearing arrangement is described in DE 195 42 079 A1,wherein one magnetic bearing element is stationarily fixed in a housingof the axial bearing, and another magnetic bearing element or elementsare releasably arranged on the rotor shaft of the spinning rotor.Different variations are proposed in this reference regarding theattachment to the rotor shaft of the magnetic bearing elements so as tothereby rotate integrally with the spinning rotor.

Some of these proposals relate to a frictional fitting of theco-rotating magnetic bearing elements on the shaft, while otherproposals relate to an interlocking connection of the co-rotatingmagnetic bearing elements, which can be easily released if required.Although a correct axial fixation of the rotor shaft on the support diskbearing arrangement is possible with these known magnetic bearingelements, and although it is furthermore assured that the spinning rotorcan be installed and removed without problems when required, it has beenshown that the frictional connection of the magnetic bearing componentwith the rotor shaft, which is basically advantageous in that it can beeasily released when required, is still capable of improvements. Thefastening of the co-rotating magnetic bearing elements on the rotorshaft is particularly problematical in connection with such magneticbearing devices, because the high number of revolutions of the spinningrotor places great demands on the balancing quality of this connection.

An open-end rotor spinning arrangement with a permanent magnet axialbearing has also become known from Austrian Letters Patent 270 459. Inthis bearing arrangement, ferromagnetic annular shoulders are arrangedat the end of the rotor shaft of a spinning rotor, and pole shoes of apermanent magnet, which is pivotably seated in this area, are placedopposite the annular shoulders. The bundling of the magnetic lines offorce of the permanent magnet, which becomes possible by means of suchan arrangement, leads to a relatively stiff fixation of the rotor shaftin the bearing wedge of the support disk bearing arrangement.

However, this type of magnetic bearing arrangement has the disadvantagethat the annular shoulders arranged on the rotor shaft clearly have alarger diameter than the rotor shaft itself. Since the larger diameterannular shoulders make considerably more difficult or even prevent theinstallation and removal of the spinning rotor, in particular themounting of its front, this known magnetic bearing arrangement has beenunable to gain acceptance in actual use.

Furthermore, a bearing for a spindle of a textile machine, which rotatesat a relatively high number of revolutions, is known from German PatentPublication DE 30 47 606 A1. Here, the spindle is supported in theradial direction by means of a three-point bearing arrangement similarto a support disk bearing, and the spindle is secured in the axialdirection by means of a magnetic bearing. At its end, the spindle has abearing area with a reduced diameter and with two ferromagnetic annularshoulders. A bushing made of a non-magnetic material is fixed in placeon the bearing housing, and a ring-shaped permanent magnet element,which is enclosed in lateral pole disks, has been embedded in it. In theinstalled state of the spindle, the ferromagnetic annular shoulders ofthe spindle shaft are located opposite the pole disks of the permanentmagnet element fixed in the static bearing element. Although this knownembodiment permits a relatively problem-free installation and removal ofthe spindle in the axial direction, this arrangement has not been ableto gain acceptance in actual use because of its lack of axial bearingrigidity.

Moreover, other bearings for spinning rotors are known from GermanPatent Publication DE 197 29 191 A1, or the later published GermanPatent Publication DE 199 10 279.1, wherein the shaft of the rotor issupported without axial thrust in the bearing wedge of a support diskbearing and is axially fixed in place by means of an axial bearing. Inthis case the axial bearing has a stationary magnetic bearing component,which can be fixed in place on the bearing housing, and a rotatablyarranged magnetic bearing component constituted by ferromagnetic annularshoulders in the area of the end of the rotor shaft. Here, the annularshoulders are constituted by recesses in the rotor shaft, which aresubsequently filled with a non-magnetic filler material. In this manner,it is intended to avoid the danger that a coating on the peripheralrunning surfaces of the support disks might be damaged by sharp-edges ofthe annular shoulders during the installation or removal of the spinningrotor.

In accordance with German Patent Publication DE 197 29 191 A1, plasticis provided as the filler material but without completely satisfactoryresults because, at the high speed of rotation of the spinning rotor,the plastic material has a tendency to “flow” after extended periods ofoperation, which results in an unacceptable imbalance of the spinningrotor.

Although these difficulties could be prevented by filling the recesseswith a non-magnetic metallic material as described in German PatentPublication DE 199 10 279.1, this filling of these recesses, for examplewith copper, can lead to an accumulation of material outside of thebearing area of the rotor shaft, which had a negative effect on thenatural oscillation behavior of the spinning rotor, in particular atnumbers of revolutions clearly above 100,000 min⁻¹.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to further improvethe known open-end spinning devices described above and to overcome thedisadvantages thereof.

The present invention is basically adapted to any open-end spinningframe of the type having a spinning rotor, a rotor shaft fixed coaxiallywith the spinning rotor, a support disk bearing arrangement defining abearing wedge for supporting therein the rotor shaft without imposingaxial thrust thereon, and a magnetic axial bearing having a bearinghousing, a stationary magnetic bearing component fixed in the bearinghousing, and a rotating magnetic bearing component arranged at the endof the rotor shaft. In accordance with the present invention, theaforestated object is attained by forming the rotating magnetic bearingcomponent to comprise at least two ferromagnetic annular shouldersdefined by adjacent recesses in the rotor shaft, wherein each annularshoulder has opposed radial faces and a generally rounded outercircumference extending therebetween and each recess has a basecircumference connected via rounded annular surfaces with the radialsurfaces of the adjacent annular shoulders. In this manner, the annularshoulders have no sharp edges so that the relatively sensitive runningsurfaces of the support disks are not damaged in the course ofinstalling and removing the spinning rotor. Furthermore, the presentinvention provides the advantage of minimizing the portion of weight ofthe rotor shaft projecting past the location of the support disk bearingarrangement.

In a preferred embodiment, the ratio of the length of the rotor shaft tothe diameter of the rotor shaft is less than about 12:1, preferablyabout 11.33:1, which makes it possible to further optimize the spinningrotor such that at high rotational speeds, especially at revolutionsgreater than 130,000 rpm, the rotor remains outside of its criticalnatural frequency.

The rotor shaft advantageously has a length greater than about 100 mm,preferably a length of about 93.5 mm. This length is noticeablyshortened in comparison with the customary length of conventional rotorshafts, which essentially is due to the area of the magnetic bearingcomponents of the rotor shaft, and advantageously raises the criticalnatural frequency of the spinning rotor to a level of revolutions whichalso provides room for further developments.

Thus, the critical natural frequency of the spinning rotor in accordancewith the invention lies at a number of revolutions which is clearlyabove the number of revolutions of rotors which can be expected in theforeseeable future.

In order to preserve the sensitive circumferential running surfaces ofthe support disks, the general rounding of the annular shoulders reducessubstantially the presence of sharp edges in the peripheral areas of theshoulders. For example, the rounding of the shoulders may beaccomplished by forming the rounded circumference with curved sectionsor bevels. On the one hand, such designs assure in a simple manner thatthe circumferential running surfaces of the support disks are notdamaged in the course of the installation or removal of the spinningrotor and, on the other hand, the relatively small curved sections orbevels do not result in any appreciable disruption of the magnetic fluxof the axial bearing. For example, the rounded sections arranged on theannular shoulders are of a size of between about 0.1 mm to about 0.5 mm,preferably 0.3 mm.

The curved sections provided in the region of the transitions betweenthe base surfaces of the recesses and the adjoining radial shoulderfaces also minimize the danger of breaking of the rotor shaft whenturning at high rotational speeds, and in particular remove any possiblenotching effect in the area of the annular shoulders and recesses. Eachof these curved sections has a size of between 0.2 and 1.5 mm,preferably 0.7 mm.

It is additionally preferred that a mechanical emergency bearing bearranged inside the magnetic axial bearing. This emergency bearing iscomprised at least partially of a highly wear-resistant ceramicmaterial, for example a ceramic pin, which is inserted into a bore ofthe bearing bushes of the axial bearing. In this case, the ceramic pinacts together with a contact surface, for example the front face of therotor shaft, arranged at a distance. Thus, during “normal” spinningoperations the stationary ceramic pin does not rest against itsoppositely rotating bearing element and, therefore, no additionalfriction occurs. However, in case of a failure, the emergency bearingprevents the magnetic bearing components from coming into directphysical contact, which would lead to considerable damage of the axialbearing.

Further details, features and advantages of the present invention willbe understood from the following disclosure of exemplary embodimentswith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side elevational view of an open-end spinningframe in accordance with the present invention, with the rotor shaft ofits spinning rotor supported, free of axial thrust, in the bearing wedgeof a support disk bearing, and fixed in place at its end by means of amagnetic axial bearing,

FIG. 2 is an enlarged view, partially in side elevation and partially incross-section, of the axial bearing of FIG. 1, with the end area of therotor shaft having a magnetic bearing component designed in accordancewith the present invention,

FIG. 3 is a side elevational view of the rotor shaft in accordance withthe present invention,

FIG. 4 is an enlarged side elevational view of the rotational magneticbearing component at the end area of the rotor shaft in accordance withthe embodiment of FIG. 2, and

FIG. 5 is another enlarged side elevational view of a rotationalmagnetic bearing component at the end area of a rotor shaft inaccordance with an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the accompanying drawings and initially to FIG. 1, anopen-end spinning unit is identified as a whole by the reference numeral1. In a known manner, the spinning unit has a rotor housing 2, in whichthe spinning cup of a spinning rotor 3 rotates at a high number ofrevolutions. The spinning rotor 3 is integrally mounted coaxially to arotor shaft 4 supported in the bearing wedge of a support disk bearingarrangement 5, and is driven peripherally by a tangential belt 6extending over the length of the machine and held frictionally againstthe shaft 4 by a contact roller 7. The rotor shaft 4 is axially fixed bymeans of a permanent magnet axial bearing 18, shown in detail in FIGS. 2and 3.

As is customary, the rotor housing 2 is open toward its front and isclosed during operation by a pivotably seated cover element 8, intowhich a channel plate (not shown in detail) with a seal 9 has been cut.The rotor housing 2 is also connected via an appropriate aspirating line10 to a suction source 11, which generates the underpressure required inthe rotor housing 2.

A channel plate adapter 12 is arranged in the cover element 8, whichholds a yarn withdrawal nozzle 13 as well as the mouth area of a fiberguide conduit 14. A small yarn withdrawal tube 15 follows the yarnwithdrawal nozzle 13. In addition, an opening roller housing 17 is fixedin place on the cover element 8, which is seated so that it is pivotableto a limited extent around a pivot shaft 16. On its rear, the coverelement 8 additionally has bearing brackets 19, 20 for seating anopening roller 21 or a sliver draw-in cylinder 22. In the area of itswharve 23, the opening roller 21 is driven by a circulating tangentialbelt 24 extending over the length of the machine, while the drivemechanism (not represented) of the sliver draw-in cylinder 22 preferablyis provided via a worm gear arrangement, which is connected with adrive-shaft 25 extending over the length of the machine.

FIG. 2 shows the axial bearing 18 in accordance with the presentinvention in detail in a sectional view. Only a support disk 54 with itsshaft 55 of the support disk bearing 5 is represented in FIG. 2. Acorresponding pair of support disks is arranged, spaced apart, in thevicinity of the spinning cup of the spinning rotor 3, as can be seen inFIG. 1.

The magnetic axial bearing 18 comprises an essentially stationarymagnetic bearing component 27, which is supported in a bearing housing26 and can be axially adjusted. The active bearing components in theform of permanent magnet rings 41 with pole rings 45 respectivelyarranged on both sides are arranged within a two-piece bearing bushing28, comprised of an inner bushing 28′ and an outer bushing 28″. Thebearing bushing elements 28′ and 28″ are screwed together by means of ascrew thread 30. The active bearing components 41 and 45 are supportedinside the inner bushing 28′ and are pressed against an annular shoulder29 arranged on the outer bushing 28″. This results on the one hand in asolid bearing structure, and on the other hand in an unproblematicalcapability for dismantling the bearing, for example for replacingindividual components arranged in the interior of the bearing.

The bearing bushing 28 is seated for axial displaceability within a bore26′ of the bearing housing 26. As a result, it is possible to adjust thestationary magnetic bearing component exactly to achieve an optimalposition in accordance with the spinning technology of the spinning cup.

To prevent twisting of the bearing bushing 28 inside the bearing housing26, a pin 32 of a bolt 33 inserted into a bore 34 engages a longitudinalgroove 31 of the bearing bushing 28. The axial adjustment of the staticbearing component 27 can be performed in a simple manner by means of apin 35 of a so-called setting gauge 36, which engages a groove 59 of thebearing bushing 28. For this purpose, the setting gauge 36 is insertedinto a bore 38 of the bearing housing 26. The axial position of thestatic bearing component 27 can be fixed in place by means of afastening screw 53, which braces the bearing bushing 28 against thebearing housing 26.

The rotatable magnetic bearing component 44 of the rotor shaft 4 can beinserted through an opening in the rotor housing 2, through the bearingwedges of the support disk bearing 5, as well as a bore 37 of theannular shoulder 29, into the stationary magnetic bearing component 27,while the remaining shaft portion 4′, which primarily is used for theradial seating of the spinning rotor 3, remains outside of the axialbearing 18.

The magnetic bearing component 44 of the rotor shaft 4 essentiallyconsists of recesses 47, which form disk-like annular shoulders 46therebetween. The rotor shaft 4 is manufactured of steel withferromagnetic properties. With the rotor shaft 4 completely insertedinto the axial bearing 18, the annular shoulders 46 are in radiallyopposed facing relationship with the pole disks 45, which are arrangedon both sides of the permanent magnet rings 41. Preferably the poledisks 45 have the same width as the annular shoulders 46. In this case,the width of each of the annular shoulders 46 preferably isapproximately 1 mm, and the width of each of the recesses 47 isapproximately 3 mm.

In addition, a support device 39 is arranged in the area of the axialbearing 18, which has a ceramic pin 42, for example, which has beeninserted into a bore of a shoulder 40 of the bearing bushing 28,preferably into the outer bushing 28″.

As indicated in FIG. 2, during “normal” spinning operations the ceramicpin 42 is at a spacing a from the rotor shaft 4 revolving at a highnumber of revolutions, which assures that no friction will occur betweenthe two components.

In case of interruptions in spinning, in particular during rotorcleaning, during which the contact roller 7 with the tangential belt 6is lifted off the rotor shaft 4 and the spinning rotor 3 is acted uponby a cleaning element arranged in a piecing cart, the support device 39prevents the rotor shaft 4 from being pivoted in a clockwise direction,based on the radial force component acting on the rotor shaft 4 in thecourse of this, and that as a result a contact between the magneticbearing components of the axial bearings 18 could occur.

As can be further seen in FIG. 2, a mechanical emergency bearing 52 isadditionally arranged inside the magnetic axial bearing 18. Thisemergency bearing 52 comprises, as indicated for example in FIG. 2, aceramic pin 56, which is fixed in place in a bore of the bearing bushing28 and which in case of emergency acts together with the front face 50′of the rotor shaft 4. Alternatively, as indicated in FIG. 5, the ceramicpin 56 can also be fastened in a bore of the rotor shaft 4 and wouldthen act together with the bottom surface 57 of the bearing bushing 28.

FIG. 3 shows a rotor shaft 4 in a general view. Here, the end of therotor shaft 4 is equipped with the magnetic bearing component 44 of thepresent invention as shown in FIG. 2 and described above. In this case,the diameter D of the rotor shaft 4 lies between about 8 mm and 9 mm,preferably 8.25 mm. The length L of the rotor shaft 4 is less than about100 mm, and preferably is 93.5 mm.

The magnetic bearing component 44 is represented in an enlarged scale inFIG. 4, and is comprised of annular shoulders 46, as well as recesses 47located therebetween. Here, the exterior diameter of the annularshoulders 46 approximately corresponds to the exterior diameter D of therotor shaft 4, while the diameter of the recesses 47 is clearly less andfor example is approximately 5 mm.

In accordance with the invention, the sharpness of the annular edges ofthe shoulders 46 is reduced in the area of their outer circumference byrounding the outer annular edges either in the form of a curved sections48, as represented in FIG. 4, or bevels 43, as indicated in FIG. 5. Ascan be seen from FIGS. 4 and 5 in, particular, the transitions betweenthe base surfaces 49 of the recesses 47 and the radial faces 50 of theannular shoulders 46 are also rounded. These curved sections identifiedby 51 are preferably slightly larger than the curved sections 48 in thearea of the outer circumference of the annular shoulders 46.

It will therefore be readily understood by those persons skilled in theart that the present invention is susceptible of broad utility andapplication. Many embodiments and adaptations of the present inventionother than those herein described, as well as many variations,modifications and equivalent arrangements, will be apparent from orreasonably suggested by the present invention and the foregoingdescription thereof, without departing from the substance or scope ofthe present invention. Accordingly, while the present invention has beendescribed herein in detail in relation to its preferred embodiment, itis to be understood that this disclosure is only illustrative andexemplary of the present invention and is made merely for purposes ofproviding a full and enabling disclosure of the invention. The foregoingdisclosure is not intended or to be construed to limit the presentinvention or otherwise to exclude any such other embodiments,adaptations, variations, modifications and equivalent arrangements, thepresent invention being limited only by the claims appended hereto andthe equivalents thereof.

1. An open-end spinning frame having a spinning rotor, a rotor shaft fixed coaxially with the spinning rotor, a support disk bearing arrangement defining a bearing wedge for supporting therein the rotor shaft without imposing axial thrust thereon, a magnetic axial bearing having a bearing housing, a stationary magnetic bearing component fixed in the bearing housing, and a rotating magnetic bearing component arranged at an end area of the rotor shaft, the rotating magnetic bearing component comprising at least two ferromagnetic annular shoulders defined by adjacent recesses in the rotor shaft, each annular shoulder having opposed radial faces and a generally rounded outer circumference extending therebetween and each recess having a base circumference connected via rounded annular surfaces with the radial faces of the adjacent annular shoulders.
 2. The open-end spinning frame in accordance with claim 1, characterized in that the ratio of the length of the rotor shaft to the diameter of the rotor shaft is less than about 12:1.
 3. The open-end spinning frame in accordance with claim 1, characterized in that the ratio of the length of the rotor shaft to the diameter of the rotor shaft is about 11.33:1.
 4. The open-end spinning frame in accordance with claim 1, characterized in that the rotor shaft has a length of less than about 100 mm.
 5. The open-end spinning frame in accordance with claim 1, characterized in that the rotor shaft has a length of about 93.5 mm.
 6. The open-end spinning frame in accordance with claim 1, characterized in that the generally rounded outer circumference of each of the annular shoulders comprises curved annular sections extending between an exterior circumferential surface and the adjacent radial faces.
 7. The open-end spinning frame in accordance with claim 6, characterized in that each of the curved sections in the area of the exterior circumferential surface has an axial dimension of between about 0.1 mm and about 0.5 mm.
 8. The open-end spinning frame in accordance with claim 6, characterized in that each of the curved sections in the area of the exterior circumferential surface has an axial dimension of about 0.3 mm.
 9. The open-end spinning frame in accordance with claim 1, characterized in that the generally rounded outer circumference of each of the annular shoulders comprises beveled annular sections extending between an exterior circumferential surface and the adjacent radial faces.
 10. The open-end spinning frame in accordance with claim 1, characterized in that the rounded annular surfaces of each recess between the base circumference thereof and the radial faces of the adjacent annular shoulders have a dimension of between about 0.2 mm and about 1.5 mm.
 11. The open-end spinning frame in accordance with claim 1, characterized in that the rounded annular surfaces of each recess between the base circumference thereof and the radial faces of the adjacent annular shoulders have a dimension of about 0.7 mm.
 12. The open-end spinning frame in accordance with claim 1, characterized in that one radial face of one of the annular shoulders forms a terminal end of the rotor shaft.
 13. The open-end spinning frame in accordance with claim 1, characterized further by a mechanical emergency bearing in the end area of the rotor shaft, the emergency bearing having at least one bearing component made of a ceramic material.
 14. The open-end spinning frame in accordance with claim 13, characterized in that the one bearing component comprises a ceramic pin.
 15. The open-end spinning frame in accordance with claim 14, characterized in that the ceramic pin is fixed in a bore of a bearing bushing of the axial bearing.
 16. The open-end spinning frame in accordance with claim 14, characterized in that the ceramic pin is fixed in a bore of the rotor shaft.
 17. A rotor shaft for a spinning rotor of an open-end spinning frame, the rotor shaft comprising: a rotating magnetic bearing component arranged at an end area of the rotor shaft, the rotating magnetic bearing component comprising at least two ferromagnetic annular shoulders defined by adjacent recesses in the rotor shaft, each annular shoulder having opposed radial faces and a generally rounded outer circumference extending therebetween, and each recess having a base circumference connected via rounded annular surfaces with the radial faces of the adjacent annular shoulders.
 18. The rotor shaft of claim 17, wherein the ratio of the length of the rotor shaft to the diameter of the rotor shaft is less than about 12:1.
 19. The rotor shaft of claim 17, wherein the ratio of the length of the rotor shaft to the diameter of the rotor shaft is about 11.33:1.
 20. The rotor shaft of claim 17, wherein the rotor shaft has a length of less than about 100 mm.
 21. The rotor shaft of claim 17, wherein the rotor shaft has a length of about 93.5 mm.
 22. The rotor shaft of claim 17, wherein the generally rounded outer circumference of each of the annular shoulders comprises curved annular sections extending between an exterior circumferential surface and the adjacent radial faces.
 23. The rotor shaft of claim 22, wherein each of the curved sections in the area of the exterior circumferential surface has an axial dimension of between about 0.1 mm and about 0.5 mm.
 24. The rotor shaft of claim 22, wherein each of the curved sections in the area of the exterior circumferential surface has an axial dimension of about 0.3 mm.
 25. The rotor shaft of claim 17, wherein the generally rounded outer circumference of each of the annular shoulders comprises beveled annular sections extending between an exterior circumferential surface and the adjacent radial faces.
 26. The rotor shaft of claim 17, wherein the rounded annular surfaces of each recess between the base circumference thereof and the radial faces of the adjacent annular shoulders have a dimension of between about 0.2 mm and about 1.5 mm.
 27. The rotor shaft of claim 17, wherein the rounded annular surfaces of each recess between the base circumference thereof and the radial faces of the adjacent annular shoulders have a dimension of about 0.7 mm.
 28. The rotor shaft of claim 17, wherein one radial face of one of the annular shoulders forms a terminal end of the rotor shaft.
 29. The rotor shaft of claim 17, further comprising: a mechanical emergency bearing in the end area of the rotor shaft, the emergency bearing having at least one bearing component made of a ceramic material.
 30. The rotor shaft of claim 29, wherein the at least one bearing component comprises a ceramic pin.
 31. The rotor shaft of claim 30, wherein the ceramic pin is fixed in a bore of a bearing bushing of the axial bearing.
 32. The rotor shaft of claim 30, wherein the ceramic pin is fixed in a bore of the rotor shaft.
 33. A rotor shaft having a rotating bearing component arranged at an end thereof for use in a spinning frame in which the rotor shaft is coaxially fixed to a spinning rotor, a support disk bearing arrangement defines a bearing wedge for supporting the rotor shaft without imposing axial thrust thereon, a magnetic axial bearing having a bearing housing with a stationary magnetic bearing component fixed in the bearing housing, said rotating bearing component comprising at least two ferromagnetic annular shoulders defined by adjacent recesses in the rotor shaft, each annular shoulder having opposed radial faces and a generally rounded out circumference extending therebetween, and each recess having a base circumference connected with the radial faces of the adjacent annular shoulders.
 34. The rotor shaft of claim 33, wherein each recess of said rotating bearing component has a rounded annular surface connecting said base circumference thereof with the radial faces of the adjacent annular shoulders.
 35. The rotor shaft of claim 34, wherein the ratio of the length of the rotor shaft to the diameter of the rotor shaft is less than about 12:1.
 36. The rotor shaft of claim 34, wherein the ratio of the length of the rotor shaft to the diameter of the rotor shaft is about 11.33:1.
 37. The rotor shaft of claim 34, wherein the rotor shaft has a length of less than about 100 mm.
 38. The rotor shaft of claim 34, wherein the rotor shaft has a length of about 93.5 mm.
 39. The rotor shaft of claim 34, wherein the generally rounded outer circumference of each of the annular shoulders comprises curved annular sections extending between an exterior circumferential surface and the adjacent radial faces.
 40. The rotor shaft of claim 39, wherein each of the curved sections in the area of the exterior circumferential surface has an axial dimension of between about 0.1 mm and about 0.5 mm.
 41. The rotor shaft of claim 39, wherein each of the curved sections in the area of the exterior circumferential surface has an axial dimension of about 0.3 mm.
 42. The rotor shaft of claim 34, wherein the generally rounded outer circumference of each of the annular shoulders comprises beveled annular sections extending between an exterior circumferential surface and the adjacent radial faces.
 43. The rotor shaft of claim 34, wherein the rounded annular surfaces of each recess between the base circumference thereof and the radial faces of the adjacent annular shoulders have a dimension of between about 0.2 mm and about 1.5 mm.
 44. The rotor shaft of claim 34, wherein the rounded annular surfaces of each recess between the base circumference thereof and the radial faces of the adjacent annular shoulders have a dimension of about 0.7 mm.
 45. The rotor shaft of claim 34, wherein one radial face of one of the annular shoulders forms a terminal end of the rotor shaft.
 46. The rotor shaft of claim 34, further comprising: a mechanical emergency bearing in the end area of the rotor shaft, the emergency bearing having at least one bearing component made of a ceramic material.
 47. The rotor shaft of claim 46, wherein the at least one bearing component comprises a ceramic pin.
 48. The rotor shaft of claim 47, wherein the ceramic pin is fixed in a bore of a bearing bushing of the axial bearing.
 49. The rotor shaft of claim 47, wherein the ceramic pin is fixed in a bore of the rotor shaft.
 50. A rotor shaft for a spinning rotor of an open-end spinning frame, the rotor shaft comprising: a rotating magnetic bearing component arranged at an end area of the rotor shaft, the rotating magnetic bearing component comprising at least two ferromagnetic annular shoulders defined by adjacent recesses in the rotor shaft, each annular shoulder having opposed radial faces and a generally rounded outer circumference extending therebetween, and each recess having a base circumference.
 51. The rotor shaft of claim 50, wherein the ratio of the length of the rotor shaft to the diameter of the rotor shaft is less than about 12:1.
 52. The rotor shaft of claim 50, wherein the ratio of the length of the rotor shaft to the diameter of the rotor shaft is about 11.33:1.
 53. The rotor shaft of claim 50, wherein the rotor shaft has a length of less than about 100 mm.
 54. The rotor shaft of claim 50, wherein the rotor shaft has a length of about 93.5 mm.
 55. The rotor shaft of claim 50, wherein the generally rounded outer circumference of each of the annular shoulders comprises curved annular sections extending between an exterior circumferential surface and the adjacent radial faces.
 56. The rotor shaft of claim 55, wherein each of the curved sections in the area of the exterior circumferential surface has an axial dimension of between about 0.1 mm and about 0.5 mm.
 57. The rotor shaft of claim 55, wherein each of the curved sections in the area of the exterior circumferential surface has an axial dimension of about 0.3 mm.
 58. The rotor shaft of claim 50, wherein the generally rounded outer circumference of each of the annular shoulders comprises beveled annular sections extending between an exterior circumferential surface and the adjacent radial faces.
 59. The rotor shaft of claim 50, wherein the rounded annular surfaces of each recess between the base circumference thereof and the radial faces of the adjacent annular shoulders have a dimension of between about 0.2 mm and about 1.5 mm.
 60. The rotor shaft of claim 50, wherein the rounded annular surfaces of each recess between the base circumference thereof and the radial faces of the adjacent annular shoulders have a dimension of about 0.7 mm.
 61. The rotor shaft of claim 50, wherein one radial face of one of the annular shoulders forms a terminal end of the rotor shaft.
 62. The rotor shaft of claim 50, further comprising: a mechanical emergency bearing in the end area of the rotor shaft, the emergency bearing having at least one bearing component made of a ceramic material.
 63. The rotor shaft of claim 62, wherein the at least one bearing component comprises a ceramic pin.
 64. The rotor shaft of claim 63, wherein the ceramic pin is fixed in a bore of a bearing bushing of the axial bearing.
 65. The rotor shaft of claim 63, wherein the ceramic pin is fixed in a bore of the rotor shaft. 